I’m a teacher. I bought this book for my own children. It’s a book about being true to yourself, even when you don’t feel like you fit in. You don’t have to be “blue” or “pink” if you feel like you fit into both categories.
Yes, it’s a book about being trans, but there are other ways to read the book, especially if your audience is young. Accepting and loving yourself. Inclusion. Tolerance. It’s a sweet book, and so of course people are going to get mad… it teaches kids acceptance, not hate!